Employee Benefit Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employer Matching Contribution, Percent of Match			6.00%
Employees’ Capital Accumulation Plan, Total expense recognized	$ 26,200,000	$ 36,400,000	$ 81,400,000	$ 118,700,000
Employees’ Capital Accumulation Plan, Company-paid contributions	14,900,000	19,300,000	53,100,000	83,700,000
Officer Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,022,000	1,186,000	3,064,000	3,559,000
Interest cost	892,000	921,000	2,676,000	2,751,000
Net actuarial loss	145,000	704,000	436,000	2,068,000
Total benefit cost	2,059,000	2,811,000	6,176,000	8,378,000
Defined benefit plan, unfunded status of plan	$ 80,200,000		$ 80,200,000		$ 75,900,000